Why Do We Yawn When We're Tired?

Yawning when you're tired is like pressing the refresh button on your brain. When you yawn, more oxygen goes into your body and more carbon dioxide comes out, it helps your brain wake up or get ready for sleep. It's also contagious! If someone else yawns nearby, you might feel the urge to do the same.

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Examples

You're at school and feel sleepy after lunch; you yawn, and your friend does too.
Your dog yawns when it's lying down on the couch after a long day of running around.
You watch a movie late at night, and suddenly start yawning, even though you’re not tired.

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Categories: Psychology · yawning,sleep,neuroscience,brain function